1. Field of the Invention
The present invention relates to a method and system for removing noise by using a change in activity pattern, in which it is recognized that an occupation pattern of a noise component included in a bio signal is different according to the activity pattern of the subject and different filters for removing noise according to each activity pattern are stored, thereby optimally removing the noise components.
2. Description of Related Art
A general sensing device for measuring a bio signal is attached to a subject such as a human and directly senses a bio signal such as an electrocardiogram signal of the subject. The sensed bio signal is used as data for determining whether there is an abnormality in the subject, via a predetermined analysis procedure. For example, when sensing an electrocardiogram signal, the electrocardiogram signal may be assessed only for whether cardiac impulse of the subject is normal and the stress load on the subject.
However, when a patch type sensor attached directly on the subject, the strength of a sensed electrocardiogram signal is less than a standard electrocardiogram and the frequency of generating an electromyogram signal acting as noise according to a position to which the sensor is attached is increased.
In addition, frequency components of noise generated according to the movement of the subject in an electrocardiogram signal are different from each other. In this case, an optimal filter for removing the frequency components generated according to the relevant movement has to be selected and applied.
For example, in an activity pattern of the subject, such as walking, jogging, and running, a noise component such as an electromyogram signal higher than 30 Hz is generated. Therefore, a filter passing a signal of less than 30 Hz has to be applied in order to remove this noise component.
On the other hand, with respect to the activity pattern of the subject performing back or stomach exercises, a noise component of the electromyogram signal continuously occurs below 0.5 Hz. In order to remove this noise component, a filter passing signals higher than 0.5 Hz has to be applied
If a filter to be applied is previously determined by considering the activity pattern of the subject, the filter may be automatically determined by recognizing the relevant activity pattern of the subject by actually sensing a bio signal, the burden of continuously changing filters may be solved.
Also, when a patch type electric potential measurement sensor, an electrocardiogram signal is weak and relatively susceptible to an electromyogram signal and baseline drift. This may be a problem generated in using any minimized electrodes. Particularly, since noises such as the electromyogram signal and baseline drift have a tendency in which patterns of noise components are different according to activity pattern, if the respective effects on the electrocardiogram according to the activity pattern is recognized, noise may be effectively removed.
Accordingly, a method of removing noise in which a previously determined filter for removing noise is selected according to the activity pattern of the subject, thereby eliminating baseline drift and electromyogram noise in sensing an electrocardiogram is required.